A lot of American actors will try that sort of bootleg British accent that's supposed to sound like...elegant, high class, etc.

You know, I think most of the time they consider that a straight up American accent will not sound refined and sophisticated. At all.

Usually they're kind of right.

Then again sometimes you get movies like Man In the Iron Mask.

1 Frenchman
1 Brit playing a Frenchman with a British accent
2 American playing a Frenchman with a British accent
And Leonardo DiCapprio. Playing the King of France. With a straight up American accent.

Go figure.